BillGuard is a free service designed to solve the problem of possibly overlooking hidden fees, billing errors or fraudulent transactions on your credit cards. It scans and analyzes your card transactions and alerts you if they match charges others have flagged as questionable.

Unless you're vigilant about thoroughly reading your credit card and debit card statements (BillGuard says 9 out of 10 people aren't), it can be easy to miss things like being double billed or spotting that small mysterious charge that might be a scam. BillGuard uses our collective consumer vigilance and its own automated tests to help protect against unauthorized and unwanted charges or even just subscriptions you've forgotten about. Each time a user verifies or flags a transaction in BillGuard, it makes BillGuard a bit smarter and strengthens its power to act as "antivirus for our bills."

If you're wary about handing over your credit card data to yet another online financial tool (healthy skepticism is a good thing), take a look at BillGuard's security information page, in which the company says they only have read-only access to your credit or debit card statements and your account login credentials are not stored.

Although you can use a service like Mint to analyze your credit card data and find weird charges, BillGuard's system is much more focused on clearly showing you questionable charges, and it emails you immediately so you can take action. BillGuard can be very helpful for those of us with credit card or debit card statements cluttered with transactions or who just want to protect against suspicious activity.